remove mm/backing-dev.c:congestion_wait_interruptible()

void clear_bdi_congested(struct backing_dev_info *bdi, int rw);

void set_bdi_congested(struct backing_dev_info *bdi, int rw);

long congestion_wait(int rw, long timeout);

long congestion_wait_interruptible(int rw, long timeout);

void congestion_end(int rw);

#define bdi_cap_writeback_dirty(bdi) \

}

EXPORT_SYMBOL(congestion_wait);

long congestion_wait_interruptible(int rw, long timeout)

{

	long ret;

	DEFINE_WAIT(wait);

	wait_queue_head_t *wqh = &congestion_wqh[rw];

	prepare_to_wait(wqh, &wait, TASK_INTERRUPTIBLE);

	if (signal_pending(current))

		ret = -ERESTARTSYS;

	else

		ret = io_schedule_timeout(timeout);

	finish_wait(wqh, &wait);

	return ret;

}

EXPORT_SYMBOL(congestion_wait_interruptible);

/**

 * congestion_end - wake up sleepers on a congested backing_dev_info

 * @rw: READ or WRITE